1. Field of the Invention
The invention relates to a non-slip floor covering and a method for its production. The special field of application of the invention concerns highly polished floor coverings, especially of mineral materials, such as stone (e.g., granite) or ceramic, which are frequently used in public buildings or buildings accessible by the public. Slipping is one of the most frequent cause of accidents in Germany. In most cases, the severity of such accidents is underestimated. In order to increase the degree of slip-resistance, both the soles of shoes and the floors must be slip-resistant. This is necessary, above all where slide-supporting media are used on the floor. In many areas of public life, as well as in private homes, it is customary to use polished, shiny tiles made of natural stone as a representative floor covering both in dry and wet areas, as well as in foyers. It is necessary to align the slip-resistant characteristics with architectural esthetics. Slip resistance is evaluated in accordance with [DIN 51097xe2x80x94Determining slip-resistant characteristicsxe2x80x94barefoot walking areas in which wetness occursxe2x80x94walk methodsxe2x80x94sloping area and DIN 51130xe2x80x94Determining slip-resistant characteristicsxe2x80x94work areas and spaces with an elevated slip riskxe2x80x94walk methodxe2x80x94sloping area] by means of a sloping area.
2. Discussion of Background Information
Measuring devices exist for measuring the stationary coefficient of friction [Fb 701; comparative test with measuring stationary coefficient of friction on floors (publication series Federal Agency for Employment Safety)].
There are various methods for creating or increasing the slip-resistant characteristics of floor coverings of natural stone. Their use largely depends on where the floor covering is to be installed or has been installed (interiors, exteriors, degree of contamination to be anticipated, etc.). The following is a short description of the most the important methods. During blasting, the desired roughness of the corresponding blasting material is cast onto the surface at high pressure. The blasting material, the hardness of which varies to a greater or lesser degree, produces irregular rough surfaces with a high degree of surface matting [DE 31 39 427].
Flame blasting produces high-energy fuel gas oxygen flames which subject the surface to be treated temporarily with a high degree of heat. The effect of the flames produces a blasting of the quartz in the upper stone region, as well as a melting of the stone sections which subsequently vitrify and adhere relatively loosely to the surface [DE 35 45 064].
Granulation is performed by means of a granulating tool (granulating hammer) which is provided with a multitude of evenly-aligned chiseling tips. While continuously moving the workpiece, the granulating hammer is impacted on the surface with a given frequency [DE 39 33 843].
The above described and similar methods, using abrasive agents or chisel-type tools, result in increased slip-resistance, while, in terms of manufacturing, surfaces are produced which are less polished, with a considerable loss of shine and, consequently, a decrease in esthetic value.
Coating surfaces, in order to increase slip resistance, results in burls on the processed surfaces to be processed [DE 33 42 266]. This method, however, only produces minor optical changes but only has a limited surface life due to inevitable abrasion.
During the chemical etching process of natural stone surfaces, above all, the feldspar components are attacked by the hydrofluoric acid-containing substances, [Information Bulletin of Federal Association for Slip-Resistance, Dept. Public Relations Work]. The damage only extends to a few micrometers, while the quartz is largely left unharmed. The loss of shine depends on the period of reaction, the change in the overall optic effect must be tested on a test surface. Currently, this method is the most practical for increasing the slip resistance of polished natural stone floors. However, this is restricted to the use of mineral floor coverings. Chemical compounds in concentrations must be adjusted to the various types of floor coverings. Due to long periods of reaction and exact adherence to concentrations, using this method for the production of tiles is either unsuitable or involves extremely high expenditure. This method is not readily suitable for plastic floor coverings. Improper handling and disposal of the hydrofluoric acid-containing substance involves increased environmental and labor protection risks.
It is the object of the present invention to provide a non-slip floor covering the surface of which can be highly polished, and a method for producing said floor covering which does not have all the disadvantages of the prior art.
It thus is the object of the present invention to propose a non-slip floor covering of the aforesaid type which, in spite of slip-resistance, has no optical disadvantages in terms of its highly-polished surface and which can be produced by a simple non-polluting method.
Further, it is the object of the present invention to develop a method of the aforesaid type which produces slip-resistance at the site of production rather than during after treatment at the site of installation of the floor covering, which is simple and non-polluting and completely retains the optical effect and esthetics of the surface of the floor covering.
Accordingly, the present invention may be directed to a non-slip floor covering that includes a plurality of depressions regularly and randomly distributed over the floor covering such that the depressions provide a suction effect.
In accordance with another feature of the present invention, the plurality of depressions includes some of which may be flat micro-craters.
In accordance with another feature of the present invention, the plurality of depressions may be substantially invisible to a human eye.
In accordance with still another feature of the present invention, the plurality of depressions some of which may be sharp-edged.
In accordance with still another feature of the present invention, the plurality of depressions some of which may have a lens-shaped geometry.
In accordance with a further feature of the present invention, the plurality of depressions some of which may have a maximal width of 0.4 mm and a depth of between 0.01 and 0.2 mm.
In accordance with a still further feature of the present invention, the regular and random distribution of the plurality of depressions may include more than 100 depressions per cm2. Further, the floor covering may be composed of a mineral material. When the mineral material is composed of granite, the distribution of the plurality of depressions may include more than 250 depressions per cm2.
In accordance with another feature of the present invention, the floor covering may be composed of a mineral material, and the mineral material may be selected from the group consisting of granite, stone and ceramic.
The present invention may also be directed to a method for producing a non-slip floor covering. The method may include directing pulsed laser beams onto a surface of the floor covering, forming micro-craters having suction effect with the directed pulsed laser beams, and randomly and regularly distributing the formed micro-craters over the surface of the floor covering.
In accordance with another feature of the present invention, the method may include selecting laser beam parameters as a function of the material of the floor covering, and the forming of micro-craters may include evaporating the material of the floor covering in accordance with the selected laser beam parameters. Further, the floor covering may be composed of a highly-polished granite material, and the method may further include selecting pulse energy ranges for the laser beam between 0.4 mJ and 1.5 mJ, selecting a pulse length between 50 ns and 250 ns, forming a diameter for micro-craters of between 0.05 mm and 0.2 mm, and providing a distance of between 0.25 and 0.8 mm between micro-craters.
In accordance with still another feature of the present invention, the floor covering may be composed of a highly-polished natural stone material, and the method may further include selecting pulse energy ranges for the laser beam between 0.4 mJ and 1.5 mJ, selecting a pulse length between 50 ns and 250 ns, forming a diameter for micro-craters of between 0.05 mm and 0.2 mm, and providing a distance of between 0.25 and 0.8 mm between micro-craters.
In accordance with a further feature of the present invention, the method may further include moving the beam in a first direction across the floor covering with one of a scanning device and deflection optics, and moving the floor covering in a second direction with a transport device for the floor covering. The first direction may be substantially perpendicular to the second direction.
In accordance with still another feature of the present invention, the directing of the pulsed laser beams may include deflecting the pulsed laser beams with a focus mirror and positioning the focus mirror to concentrate the pulsed laser beams onto the surface of the floor covering.
In accordance with yet another feature of the present invention, the distributing of the plurality of micro-craters being one of randomly distributed and regularly distributed.
Other advantageous embodiments and features of the present invention may be ascertained by reviewing the following detailed description of the present invention and the accompanying figures.